on call/midnight interruptions

last night the phone rang at 2:30 a.m. inviting me to come to the hospital to handle an emergency, I quickly drove there took care of the patient and got back into bed at about 4:00 a.m., turned off my alarm clock so I would be able to sleep past 6:30 and put my APAP on again.
This morning when I got up at about 8:45 i found that the pressure needed had been only 7.2 which is about as low as it ever gets, my AHI was down to 2, and my AI was 0.
Is it good for sleep apnea to drive out to the emergency room and back in the middle of the night? Do any of the other emergency responders here find they have the same experience? Or is it that a shorter sleep is less likely to be deep enough to need a really high pressure to keep the apneas away?

Apneas are generally highest during REM sleep, which, if I recall right, doesn't occur until late in the night... it takes quite awhile to get into REM, if memory serves. So after the interruption, you may have never made it into REM, meaning the average pressure used was lower than usual.

Just a guess.

When I get up at 5 am for work my numbers are much better than when I sleep in naturally.